Project Summary The principal objective of this project is to develop a VesiVax vaccine against Aspergillus fumigatus. The studies proposed in this SBIR Phase II application will be focused on continuing the development of a lead candidate VesiVax vaccine containing recombinantly engineered antigens corresponding to Aspf3 and Aspf9. In the SBIR Phase I studies, we evaluated VesiVax vaccine candidates in a clinically relevant animal model for the ability to protect against a pulmonary Aspergillus challenge. From the SBIR Phase I studies, the most effective VesiVax vaccine candidate was identified and selected for advancement to clinical evaluation and development of a commercial product. In the proposed SBIR Phase II studies, our product development and commercialization efforts will be focused on using the VesiVax vaccine to prevent or ameliorate disease in the primary patient population, immunocompromised hosts such as those individuals undergoing a solid organ transplant, bone marrow transplant or cancer chemotherapy. In these patients, the opportunity exists to immunize the patient prior to the onset of immunosuppression, with the goal that the acquired resistance from the vaccine can carry over through the course of the immunosuppression, thus reducing patient mortality and infection with Aspergillus.